In U.S. Pat. No. 3,866,052, commonly-assigned herewith, methods for use in defining the spatial location of a point on an object surface involve the practice of projecting radiant energy onto the surface through digital mask structure, i.e., masks having respectively discrete energy transmissive and energy non-transmissive extents. In the preferred practice of the '052 patent, differently configured masks establish diverse irradiated segments of the projection field and are used successively. Records made in corresponding succession are examined to identify those records in the succession of records which contain, or do not contain, a representation of the illumination of each surface point of interest. Digital signal patterns are generated from the record succession unique for surface points which are in different projection field segments. These signals, together with information as to the positional location of surface points in the two-dimensional records and the spatial location of the recording lens node enable transition from two-dimensional data to spatial position determination. The lens node and record positional information establish a line of sight to the surface point and the digital signals identify the location of such point along the line of sight.
Another practice for attaining the purpose of the '052 patent is set forth in copending application Ser. No. 838,835, filed on Oct. 3, 1977 and also commonly assigned herewith. In such alternative practice, radiant energy is projected into the projection field with the intensity, or other characteristic, of the radiant energy conforming successively per projection to plural different patterns, e.g., sine, cosine or like functions, along an axis transverse to the direction of the projection field. Records are made of object-reflected radiant energy and the line of sight distance to the object surface point is derived from the records as fully discussed in such '835 application.
The foregoing practices and other practices discussed in the '052 patent and '835 application rely upon the projection of patterned radiant energy and use of masks or like energy patterning measures. In such aspect, these practices require measures of care in mask preparation, placement and use. These highly efficient practices have correspondingly increased costs in implementation and use.
Prior art patents are noted and discussed in the statement to be filed herein pursuant to 37 CFR 1.97 and 1.98.